They were said to be asleep when one or more of the women woke to find the man in the suite at 1.50 am.

All three were attacked with a hammer which the assailant abandoned after he fled the scene.

The most seriously injured woman is said to be critical but stable. She has been placed in an induced coma by surgeons in a bid to stabilise her condition.

The two other women also suffered serious head injuries but their conditions are not life threatening.

Hasan Mohamed, 28, also from the UAE, was woken up by terrified screaming from the suite where the women were attacked.

The businessman, on holiday with his wife and sister, said: "I heard horrific screaming. The woman was desperate she was shouting 'I regret coming here, they are bleeding. My sister is bleeding from the head, please help'.

“She kept saying she regretted coming, it was horrible to hear. I know security were called. There is security everywhere in the hotel. At first I was scared for my family but I have been reassured. The hotel said that things like this only happen once ever hundred years.

"Everybody in the UAE is talking about this terrible attack. We are all in shock. I will never forget those screams."

He and his family are on a six day break.

He added: "This will not stop us coming to London. We love it here."

One hotel employee said : “I went up the seventh floor after receiving a call. I heard aggressive shouting. I opened the door and saw blood everywhere. I closed the door immediately. Police were called and they were there within three minutes.”

The women were part of a larger group of wealthy visitors who are thought to have been visiting London and staying on the same floor.

There were also reported to be two or three security guards on duty at the hotel at the time.

Police said there was no sign of forced entry on the hotel room and they were keeping an open mind about the motive.

One possibility is that the intruder was an opportunistic hotel thief who went beserk when confronted by the women. Another is that they were deliberately targeted because they appeared wealthy after being spotted earlier the previous day.

Detectives are trawling through CCTV images from the hotel as well as footage from a food and wine store opposite the hotel.

Forensic officers are expected to spend several days examining the scene at the 1,000 room hotel in Great Cumberland Place.

Rooms at the hotel start at £140 a night and rise to more than £400-a-night for the Jimi Hendrix Suite, named after the room where the guitar legend gave his last-ever interview in 1970.

The investigation into the incident is being led by detectives from the Homicide and Major Crime Command.

Detective Chief Inspector Andy Chalmers said: “This was an unusually violent attack on three women and I am very keen to speak with anyone who was in or around the hotel between 1am and 2am on Sunday morning.

“Did you see or hear anything that could be of use to my officers? If so, we would like to hear from you as soon as possible.”

A Met spokesman said: “At this stage, it is believed that a single male suspect entered a guest bedroom on the seventh floor of the building, where three women and three children were sleeping in adjoining rooms.

“Detectives believe that the suspect was disturbed when some of the occupants of the room woke up, and the three women were subsequently assaulted with a hammer which was later recovered at the scene.”

There have been no arrests.

A spokesman for Guoman Hotels, which runs the Cumberland, said: “We are very concerned about the people who were injured and are doing everything we can to help the police with their enquiries.”